Everywhere i look i see vessel's (vase's that can be turned in to diffusers)
Theres a couple of rules.
Glass, narrow neak. Can be any size
"i have tried that one". (Bigger reed diffuser in another post).
An dark glass is better. As they dont let the oils evaporate as fast. So below is my empty bottle of medicine. I have been unwell. But better now. 😁